March 19, 2013

Previously Unknown Giant Radio Galaxy Discovered By LOFAR

Astronomers have discovered a previously unknown gigantic radio galaxy using the powerful International LOFAR Telescope (ILT).

The team was browsing the first set of photos taken during LOFAR's first all-sky imaging survey known as the Multi-frequency Snapshot Sky Survey (MSSS).

While browsing the first set of MSSS images, ASTRON astronomer Dr. George Heald found a new source of radio emission the size of the full moon projected on the sky. The radio emission detected is associated with material being ejected from one member of an interacting galaxy triplet system tens to hundreds of millions of years ago.

The extent of the material found is larger than the galaxy system itself, extending millions of light years across intergalactic space. The new galaxy is a member of a class of objects known as Giant Radio Galaxies (GRGs). These are a type of radio galaxy with extremely large physical size, which suggests they are very old or very powerful.

LOFAR is able to find new GRGs because it is extremely sensitive to these large objects and is able to operate at such low frequencies which are well suited to observing old sources.

The center of the new GRG is associated with one member of a galaxy triplet known as UGC 09555. The central galaxy is located about 750 million light years away from Earth. The central radio source had been known before and has a flat radio spectrum, which is a feature commonly found among giant radio galaxies.

The MSSS survey is still ongoing and astronomers hope to use it to discover many new sources. The survey is a concerted effort to image the entire northern sky at very low radio frequencies. The primary aim of the survey is to perform an initial shallow scan of the sky to create an all-sky model that helps support the calibration of much deeper observations.

LOFAR began mapping the Universe at very low energy wavelengths back in April 2010. The telescope is digital, giving it the ability to scan multiple directions in the sky at once. Having the ability to detect the electromagnetic spectrum will allow scientists to study new astrophysical phenomena. Astronomers hope to use LOFAR to study the formation of the very first stars in the universe.

The telescope helped astronomers observe some very interesting black hole behavior last October. ASTRON astronomers said they used LOFAR to observe a black hole blowing a giant bubble of plasma. Black holes have been known to spit out matter, and when this happens, they create a thin stream of particles that travel at nearly the speed of light. These bubbles are filled with a radio emitting plasma, which is visible to telescopes like LOFAR that detect radio waves.